1. Field of the Invention
Embodiments of the present invention generally relate to apparatus and methods for processing a substrate. More particularly, embodiments of the present invention provide apparatus and methods for positioning a substrate in a processing chamber using capacitive sensors.
2. Description of the Related Art
During semiconductor processing, non-contact measurement methods are usually used to detect and control the position of the substrate being processed because the stringent requirements for cleanness and sensitivity to particle contamination. Optical sensors are typically used in non-contact substrate position detection and control.
However, optical sensors cannot be placed inside the process chamber due to the materials used to construct the optical sensors. Therefore, optical sensors typically detect the position of a substrate in a processing chamber through optical windows formed through chamber walls. The optical windows cloud up due to deposition of processing gases inside the processing chamber causing measurement of the optical sensors to drift and lose accuracy absent frequent cleaning of the optical windows.
Optical sensors for detecting a substrate location are generally positioned above and/or below the substrate. One or more processing related chamber components, for example a pedestal, a showerhead, heating lamps, or a substrate susceptor, are generally positioned above or below a substrate being processed. Thus, it is also challenging to find a location to place an optical window in a processing chamber.
Therefore, there is a need for improved non-contact measurement apparatus and methods for detect and control substrate position in a processing chamber.